The present invention relates to a semiconductor device, and more particularly to a technique which is effective when applied to the formation of an electrode in the case of employing a semiconductor film for leading out the electrode.
In, for example, a bipolar LSI of SICOS (Side Wall Base Contact) structure, the base of a bipolar transistor is led out by a boron-doped polycrystalline Si (silicon) film, on which an Al-alloy electrode is formed (refer to, for example, the official gazette of Japanese Patent Application Laid-open No. 1556/1981).
Besides, the emitter, base and collector of a bipolar transistor are led out by multilayer films each consisting of a polycrystalline silicon film and platinum silicide (PtSi), and aluminum electrodes (wiring layers) are formed on the polycrystalline silicon films (described in, for example, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. SC-15, No. 4, AUGUST 1980, pp. 455-458).
Hereinbelow, for the sake of convenience, the expression "electrode" shall sometimes refer to, for example, a lead-out conductor layer which is connected near the contact hole of an aluminum wiring layer or to a base, emitter or collector or a source or drain diffused layer.